Warts are one of several soft tissue conditions of the foot that can be quite painful. They are caused by a virus and can appear anywhere on the skin. Those that appear on the sole of the foot are called plantar warts. Children, especially teenagers, tend to be more susceptible to warts than adults. Some people seem to be immune to warts.

The virus that causes warts generally invades the skin through small or invisible cuts and abrasions. The plantar wart is often contracted by walking barefoot on dirty surfaces or littered ground where the virus is lurking. The causative virus thrives in warm, moist environments, making infection a common occurrence in communal bathing facilities.

If left untreated, warts can grow to an inch or more in circumference and can spread into clusters of several warts; these are often called mosaic warts. Like any other infectious lesion, plantar warts are spread by touching, scratching, or even by contact with skin shed from another wart. The wart may also bleed, creating another route for spreading. Occasionally, warts can spontaneously disappear after a short time, and, just as frequently, they can recur in the same location.

Most warts are harmless, even though they may be painful. They are often mistaken for corns or calluses, which are layers of dead skin that build up to protect an area which is being continuously irritated. The wart, however, is a viral infection.

Plantar warts tend to be hard and flat, with a rough surface and well-defined boundaries; warts are generally raised and fleshier when they appear on the top of the foot or on the toes. Plantar warts are often gray or brown (but the color may vary), with a center that appears as one or more pinpoints of black. It is important to note that warts can be very resistant to treatment and have a tendency to reoccur.

When plantar warts develop on the weight-bearing areas of the foot (the ball of the foot, or the heel, for example), they can be the source of sharp, burning pain. Pain occurs when weight is brought to bear directly on the wart, although pressure on the side of a wart can create equally intense pain.

Self-treatment is generally not advisable. Over-the-counter preparations contain acids or chemicals that destroy skin cells, and it takes an expert to destroy abnormal skin cells (warts) without also destroying surrounding healthy tissue. Self-treatment with such medications especially should be avoided by people with diabetes and those with cardiovascular or circulatory disorders. Never use these medications in the presence of an active infection.

It is wise to consult a podiatrist when any suspicious growth or eruption is detected on the skin of the foot in order to ensure a correct diagnosis. It is possible for a variety of more serious lesions to appear on the foot, including malignant lesions such as carcinomas and melanomas. Although rare, these conditions can sometimes be misidentified as a wart.

It is possible that your podiatrist will prescribe and supervise your use of a wart-removal preparation. More likely, however, removal of warts by a simple surgical procedure, performed under local anesthetic, may be indicated.

Lasers have become a common and effective treatment. A procedure known as CO2 laser cautery is performed under local anesthesia in either your podiatrist's office surgical setting or an outpatient surgery facility. The laser reduces post-treatment scarring and is a safe form for eliminating wart lesions.

• Avoid walking barefoot

• Change shoes and socks daily

• Keep feet clean and dry

• Check children's feet periodically

• Avoid direct contact with warts from other persons or from other parts of the body

• Do not ignore growths on, or changes in, your skin

• Visit your podiatrist as part of your annual health checkup